For the treatment of patients suffering from chronic problems caused by long-term overstressing of soft tissues of the locomotor system or from certain other chronic complaints (ankylosing spondylitis, spondylarthritis) electrotherapy devices have been widely used for a long time which are adapted to be applied by the patient at home for self-therapy. Most of these devices are based on transcutaneous nerve stimulation (TNS machines).
DE-A-31 51 180 and U.S. Pat. No. 4,790,319 describe an electrotherapy device and a corresponding method for the local, non-invasive treatment of tissues by affecting their metabolism by means of DC pulses in the frequency range of 10 Hz to 10 kHz and particularly of 250 Hz to 5 kHz at voltages of up to 25 V, particularly up to 17 V, the average current being limited to a maximum of about 300 .mu.A. According to this prior art, the DC pulses are applied by means of a large-surface electrode which is fixedly applied to the body in a neutral region and a small, pin-shaped electrode allowing a point-like contact with the skin within the treated region. The state of the tissue at the treated point may be determined objectively by measuring the change of the average value of the current flowing in the patient circuit with time. The response curve of a normal tissue is such that the average current, I.sub.av, first increases with time and then reaches a saturation value after a very short time interval of a few seconds. An abnormal tissue status may be detected easily because it results in a quite different characteristic of the time dependence of I.sub.av which may show several inflection points before reaching a saturation value which is normally lower than the saturation value of a normal tissue, or which decreases after having reached a maximum value. By applying the pin-shaped electrode sequentially in a matrix-like manner to a plurality of points within the treated region the physiological status of the respective tissue may be determined, the application of the DC pulses simultaneously leading to a remarkable improvement of the physiological status of the tissue which may last for a relatively long time period.
The electrobiochemical interactions of the electric current with the structure of the living tissues leads to an increase in the local blood microcirculation, a recession of oedemas in the treated region and to a myorelaxative effect around the treated point. Such devices, however, cannot be applied by the patient himself at home without a special training with respect to the method of treatment because the pin-shaped electrode must be applied in a sequential manner to a plurality of points in the treated region, and especially with respect to the interpretation of the readings of the current measuring instrument. The time interval necessary for the preparation (fixation of electrodes) and the treatment itself usually lasts more than 10 or 20 minutes. Furthermore, devices for continuous electrostimulation to be worn by the patient may cause severe problems due to allergic reactions of the skin under the electrodes and possible electrolytic deterioration of tissues. Because of these deficiencies, these devices are often used only for a very short period of time which may result in a further development of the disease.
It is the object of the present invention to provide a method and an apparatus for the controlled local, non-invasive application of DC pulses to human and animal tissues which are particularly suited for the electrostimulation of the human and animal body and facilitate the multipoint treatment of the treated region by use of a specific design of the electronic circuitry between the pulse generator and the electrodes, and a specific design of the electrode to be applied to the treated region.